The present invention relates to a lift arm assembly using a folding linkage, including guide links to provide for a desired path of movement of the outer end of the lift arm assembly, which is used for supporting a bucket, or implement. The folding linkage includes main support links that are pivotally mounted at a lower rear portion of the skid steer loader frame, and extend uprightly, and side lift arms pivoted to the main support links. Hydraulic cylinders acting between the main support links and lift arms raise and lower the lift arms while the arms are guided in a path by guide links attached to forward portions of the frame. The lift arm assembly is sturdy, easily operated, and provides a substantially vertical path of movement of the outer ends of the lift arm assembly.
In the prior art, a number of different types of linkages have been used to guide the outer ends of loader lift arms in a vertical or “S” shaped path, many of the linkages are very successful. In particular, U.S. Pat. Nos. 5,169,278 and 6,474,933 show linkages for obtaining a generally vertical paths using multiple link lift arm assemblies. The hydraulic actuators used for each of these prior art loader lift arms have base ends anchored to the frame of the skid steer loader. Also, the lift arms are pivotally connected to upper ends of frame uprights.
Another type of extendable reach lift arm assembly is disclosed in U.S. Pat. No. 3,802,589, wherein the lift arms are attached to a movable frame that is pivotally mounted at a lower edge of the truck or vehicle frame, with at least one pair of hydraulic actuators needed for operating the lift arm assembly. A loader lift arm assembly that is guided by a linkage supported at an upper, forward side of a loader cab is shown in U.S. Pat. No. 5,542,814.
Skid steer loaders typically have a cross member that connects the lift arm supports above the engine compartment and to the rear of the cab. The upper cross member hinders access to components below the cross member.